Add Extism PDK (#258)

---------

Signed-off-by: Glenn Lewis <[email protected]>

apps/Extism/DEPS

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+../../lib/pdk/*.v3
+../../lib/util/*.v3

apps/Extism/README.md

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+# apps/Extism
+
+Here are a few [Extism] plugins written using the Virgil programming language.
+
+[Extism]: https://extism.org/
+
+* [greet](greet)
+* [count-vowels](count-vowels)
+* [http-get](http-get)
+
+## Build
+
+To build the examples, change your directory to this one (`apps/Extism`)
+and type:
+
+```bash
+$ ./build.sh
+```
+
+## Run
+
+To run all the examples with the [Extism CLI], type:
+
+```bash
+$ ./run.sh
+```
+
+[Extism CLI]: https://github.com/extism/cli

apps/Extism/TARGETS

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+wasm

apps/Extism/assets/simulatedExtismSdk.js

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+// This is a simulated Extism SDK written in JavaScript in order to assist
+// in the debugging of the MoonBit Extism PDK.
+
+// Adapted from: https://dmitripavlutin.com/timeout-fetch-request/
+export const fetchWithTimeout = async (resource, options = {}) => {
+  const { timeout = 8000 } = options  // 8000 ms = 8 seconds
+
+  const controller = new AbortController()
+  const id = setTimeout(() => controller.abort(), timeout)
+  const response = await fetch(resource, {
+    ...options,
+    signal: controller.signal,
+  })
+  clearTimeout(id)
+  return response
+}
+
+// `log` and `flust` are useful for debugging the wasm-gc or wasm targets with `println()`:
+export const [log, flush] = (() => {
+  var buffer = []
+  function flush() {
+    if (buffer.length > 0) {
+      console.log(new TextDecoder("utf-16").decode(new Uint16Array(buffer).valueOf()))
+      buffer = []
+    }
+  }
+  function log(ch) {
+    if (ch == '\n'.charCodeAt(0)) { flush() }
+    else if (ch == '\r'.charCodeAt(0)) { /* noop */ }
+    else { buffer.push(ch) }
+  }
+  return [log, flush]
+})()
+
+const memory = new WebAssembly.Memory({ initial: 1, maximum: 1, shared: false })
+const fakeAlloc = { offset: 0, buffers: {} }
+const alloc = (lengthBigInt) => {
+  const offset = fakeAlloc.offset
+  const length = Number(lengthBigInt)
+  fakeAlloc.buffers[offset] = {
+    offset,
+    length,
+    buffer: new Uint8Array(memory.buffer, offset, length),
+  }
+  fakeAlloc.offset += length
+  return BigInt(offset)
+}
+const allocAndCopy = (str) => {
+  const offsetBigInt = alloc(BigInt(str.length))
+  const offset = Number(offsetBigInt)
+  const b = fakeAlloc.buffers[offset]
+  for (let i = 0; i < str.length; i++) { b.buffer[i] = str.charCodeAt(i) }
+  return offsetBigInt
+}
+const decodeOffset = (offset) => new TextDecoder().decode(fakeAlloc.buffers[offset].buffer)
+const lastHttpResponse = { statusCode: 0 }
+const http_request = async (reqOffsetBigInt, bodyOffsetBigInt) => {
+  const req = JSON.parse(decodeOffset(reqOffsetBigInt))
+  const body = bodyOffsetBigInt ? decodeOffset(bodyOffsetBigInt) : ''
+  console.log(`http_request: req=${JSON.stringify(req)}`)
+  console.log(`http_request: body=${body}`)
+  const fetchParams = {
+    method: req.method,
+    headers: req.header,
+  }
+  if (body) { fetchParams.body = body }
+  const response = await fetchWithTimeout(req.url, fetchParams)
+  const result = await response.text()
+  console.log(`result=${result}`)
+  lastHttpResponse.statusCode = response.status
+  return allocAndCopy(result)
+}
+const http_status_code = () => lastHttpResponse.statusCode
+
+export const configs = {}  // no configs to start with
+export const vars = {}  // no vars to start with
+
+export const inputString = { value: '' }  // allows for exporting
+
+export const importObject = {
+  "extism:host/env": {
+    alloc,
+    config_get: (offsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      const key = decodeOffset(offset)
+      // console.log(`config_get(${offset}) = configs[${key}] = ${configs[key]}`)
+      if (!configs[key]) { return BigInt(0) }
+      return allocAndCopy(configs[key])
+    },
+    free: () => { }, // noop for now.
+    http_request,
+    http_status_code,
+    input_length: () => BigInt(inputString.value.length),
+    input_load_u8: (offsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      if (offset < inputString.value.length) { return inputString.value.charCodeAt(offset) }
+      console.error(`input_load_u8: wasm requested offset(${offset}) > inputString.value.length(${inputString.value.length})`)
+      return 0
+    },
+    length: (offsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      const b = fakeAlloc.buffers[offset]
+      if (!b) { return BigInt(0) }
+      // console.log(`length(${offset}) = ${b.length}`)
+      return BigInt(b.length)
+    },
+    load_u8: (offsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      const bs = Object.keys(fakeAlloc.buffers).filter((key) => {
+        const b = fakeAlloc.buffers[key]
+        return (offset >= b.offset && offset < b.offset + b.length)
+      })
+      if (bs.length !== 1) {
+        console.error(`load_u8: offset ${offset} not found`)
+        return 0
+      }
+      const key = bs[0]
+      const b = fakeAlloc.buffers[key]
+      const byte = b.buffer[offset - key]
+      // console.log(`load_u8(${offset}) = ${byte}`)
+      return byte
+    },
+    log_info: (offset) => console.info(`log_info: ${decodeOffset(offset)}`),
+    log_debug: (offset) => console.log(`log_debug: ${decodeOffset(offset)}`),
+    log_error: (offset) => console.error(`log_error: ${decodeOffset(offset)}`),
+    log_warn: (offset) => console.warn(`log_warn: ${decodeOffset(offset)}`),
+    output_set: (offset) => console.log(decodeOffset(offset)),
+    store_u8: (offsetBigInt, byte) => {
+      const offset = Number(offsetBigInt)
+      Object.keys(fakeAlloc.buffers).forEach((key) => {
+        const b = fakeAlloc.buffers[key]
+        if (offset >= b.offset && offset < b.offset + b.length) {
+          b.buffer[offset - key] = byte
+          // console.log(`store_u8(${offset})=${byte}`)
+          // if (offset == b.offset + b.length - 1) {
+          //   console.log(`store_u8 completed offset=${key}..${offset}, length=${b.length}: '${decodeOffset(key)}'`)
+          // }
+        }
+      })
+    },
+    var_get: (offsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      const key = decodeOffset(offset)
+      // console.log(`var_get(${offset}) = vars[${key}] = ${vars[key]}`)
+      if (!vars[key]) { return BigInt(0) }
+      return vars[key]  // BigInt
+    },
+    var_set: (offsetBigInt, bufOffsetBigInt) => {
+      const offset = Number(offsetBigInt)
+      const key = decodeOffset(offset)
+      // console.log(`var_set(${offset}, ${bufOffsetBigInt}) = vars[${key}]`)
+      vars[key] = bufOffsetBigInt
+    },
+  },
+  spectest: { print_char: log },
+}

apps/Extism/build.sh

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+#!/bin/bash -ex
+v3c \
+  -entry-export=_initialize \
+  -heap-size=500m \
+  -main-export=_initialize \
+  -output=greet \
+  -target=wasm \
+  greet/Greet.v3 $(cat DEPS)
+
+v3c \
+  -entry-export=_initialize \
+  -heap-size=500m \
+  -main-export=_initialize \
+  -output=count-vowels \
+  -target=wasm \
+  count-vowels/CountVowels.v3 $(cat DEPS)
+
+v3c \
+  -entry-export=_initialize \
+  -heap-size=500m \
+  -main-export=_initialize \
+  -output=http-get \
+  -target=wasm \
+  http-get/HttpGet.v3 $(cat DEPS)

apps/Extism/count-vowels/CountVowels.v3

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+// `defaultVowels` represents the default set of vowels
+// if the host provides no "config.vowels" string.
+def defaultVowels = "aeiouAEIOU";
+
+// `VowelReport` represents the JSON struct returned to the host.
+class VowelReport {
+	var count: int;
+	var total: int;
+	var vowels: string;
+
+	new(count, total, vowels) {}
+
+	def toJson() -> string {
+		var b = StringBuilder.new();
+		b.put1("{\"count\":%d,", count);
+		b.put1("\"total\":%d,", total);
+		b.put1("\"vowels\":\"%s\"}", vowels);
+		return b.toString();
+	}
+}
+
+def getTotal() -> int {
+	match (Var.getInt("total")) {
+		Some(total) => return total;
+		None => return 0;
+	}
+}
+
+def storeTotal(total: int) {
+	Var.setInt("total", total);
+}
+
+def getVowels() -> string {
+	match (Config.get("vowels")) {
+		Some(s) => return s;
+		None => return defaultVowels;
+	}
+}
+
+// Exported: `count_vowels` reads the input string from the host, reads the "vowels"
+// config from the host, then counts the number of vowels in the input
+// string and keeps a running total (over multiple iterations)
+// in the host's "total" var.
+// It sends the JSON `VowelReport` to the host via its output data channel.
+// It returns 0 to the host on success.
+def count_vowels() -> int {
+	def input = Host.inputString();
+	//
+	def vowels = getVowels();
+	def vowelsArr = Array<byte>.!(vowels);
+	def count = Arrays.filter(input, Arrays.contains(vowelsArr, _)).length;
+	//
+	def total = getTotal() + count;
+	storeTotal(total);
+	//
+	def jsonStr = VowelReport.new(count, total, vowels).toJson();
+	Host.outputString(jsonStr);
+	return 0;
+}
+
+// Unused.
+def main() {
+}
+
+export count_vowels;
+
+// Hack to compile to wasm: provide Virgil identifiers that cannot be found:
+component System {
+	def error(s1: string, s2: string) {}
+}

apps/Extism/count-vowels/README.md

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+# CountVowels
+
+The `CountVowels.wasm` plugin can be run from the top-level of the repo by
+typing:
+
+```bash
+$ ./build.sh
+$ ./scripts/python-server.sh
+```
+
+Then open your browser window to:
+http://localhost:8080/examples/count-vowels

apps/Extism/count-vowels/index.html

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+<!DOCTYPE html>
+<html>
+
+<head></head>
+
+<body>
+  <script type="module">
+    import { configs, flush, importObject, inputString } from '/assets/simulatedExtismSdk.js'
+
+    const wasmUnderTest = '/count-vowels/CountVowels.wasm'
+
+    // WebAssembly.instantiateStreaming(fetch("/target/wasm-gc/release/build/examples/count-vowels/count-vowels.wasm"), importObject).then(
+    WebAssembly.instantiateStreaming(fetch(wasmUnderTest), importObject).then(
+      (obj) => {
+        console.log('Using simulated Extism SDK...')
+        obj.instance.exports._initialize()
+        // configs.vowels = 'aeiouyAEIOUY'
+        inputString.value = 'Once upon a dream'
+        obj.instance.exports['count_vowels']()
+        inputString.value = 'eight more vowels yo'
+        obj.instance.exports['count_vowels']()
+        flush()
+      }
+    )
+
+    // Next, use the official Extism JavaScript SDK:
+    // Read the JS SDK docs at: https://extism.github.io/js-sdk/
+    const extism = await import('https://esm.sh/@extism/extism')
+
+    const plugin = await extism.createPlugin(
+      fetch(wasmUnderTest),
+      { useWasi: true }
+    )
+
+    console.log('Using official Extism JavaScript SDK...')
+    let out = await plugin.call('count_vowels', 'from official Extism JavaScript SDK')
+    console.log(out.text())
+    out = await plugin.call('count_vowels', 'eight more vowels yo ho')
+    console.log(out.text());
+  </script>
+</body>
+
+</html>

apps/Extism/greet/Greet.v3

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+// Exported: `greet` reads the input string from the host and writes a
+// greeting to the host's output string.
+// It returns 0 to the host on success.
+def greet() -> int {
+  def input = Host.inputString();
+  var b = StringBuilder.new();
+  b.puts("Hello, ");
+  b.puts(input);
+  b.puts("!");
+  Host.outputString(b.toString());
+  return 0; // success
+}
+
+// Unused.
+def main() {
+}
+
+export greet;
+
+// Hack to compile to wasm: provide Virgil identifiers that cannot be found:
+component System {
+  def error(s1: string, s2: string) {}
+}

apps/Extism/greet/README.md

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+# Greet
+
+The `Greet.wasm` plugin can be run from the apps/Extism dir of the repo
+(the parent of this dir) by typing:
+
+```bash
+$ ./build.sh
+$ ./scripts/python-server.sh
+```
+
+Then open your browser window to:
+http://localhost:8080/greet